Method of preparing a powdered carbonaceous material for combustion engines



April 19, 1938. A. POTT 2,114,456

METHOD OF PREPARING A POWDERED CABBONACEOUS MATERIAL FOR COMBUSTION ENGINES Filed April 5, 1935 Rummy mm INVENTOR ALFRED POTT A ORNEY Patented Apr. 19, 1938 UNITED STATES PATENT OFFICE ENGINES Alfred Pott, Essen-on-the-Ruhr, Germany Application April 5, 1935, Serial No. 14,793

In Germany October 17, 1934 -6 cani e (01. 44-1) This invention relates to a method of preparing carbonaceous powdered fuel material. for combustion engines, particularly those of the Diesel type. In such engines, air for combustion is compressed and thereby heated-to such an extent that the fuel is automatically ignited at the desired moment. To this effect, in engines using liquid fuel, the latter is introduced into the highly compressed and very hot air by means 10 of a stream of more highly compressed air. In engines provided with pistons, the liquid fuel is thus injected just before the piston approaches the end of its stroke of compression. In engines to be fed with powdered solid fuel material, however, difficulties have been experienced when the fuel was simply injected. No complete comdrops of liquid fuel. Therefore, it is advisable to-introduce the powdered carbonaceous material into the combustion air in ample time before the temperature of ignition is reached, in order to permit the fuel to be thoroughly heated.

In such engines another difficulty has been encountered due to the ash content in the fuel material. Ashes in amounts sufficient to grind off the cylinder and piston surfaces remain in the machine after combustion. The lubricating oil circulating in the machine transports the ash to other sensitive parts of the machine, resulting in considerable wear within a short time of operation. I

It is an object of the invention to present a carbonaceous powdered fuel material in a state of high purity, practically free from ash.

It is a further object of the invention to present the powdered carbonaceous fuel material in a state of high activity. w

It is still another object. of the invention to render the combustion, calculated upon the original solid fuel m'aterial, very effective.

According to the invention, no natural carbosmaller active surface compared with finest cause of the absence not only of incombustible material but of constituents which tend to increase the fuels heat capacity as well.

Various processes of manufacturing such extracts of goal, lignite, peat, etc. are known, using organic solvent media atelevated temperatures and, preferably, raised pressure during extraction. All these extracts of coal, lignlte, etc. may be used for the purposes of the invention provided they are .sufiiciently free or freed of incombustible residues. If the normal purity of the extracts is still insufficient, filtration has to be effected preferably underraised pressure and at highly elevated temperatures.

Furthermore, in order to obtain great efll- 15 ciency of the original fuel material, high yields of extracts are imperative. For this purpose, the invention uses 'a method of producing the extracts based onthe following observation. If

e..g. coal is treated in an autoclave with a suitable solvent medium, such as a mixture of lower and higherboiling oils, thereby gradually raise ing the temperature and registering the rising pressure in the autoclave by means of an indicator, a sudden increase of pressure can be ob- 25 servedat a certain temperature. This is due to the fact that a decomposition of the material under treatment takes place whereby gases are evolved. Therefore, if the temperature at a subsequent treatment of material of the same 30 kind, with the same solvent media, remains a few degrees centigrade below the temperature of decomposition, so established by a previous treatment, a certain yield of extracts can be obtained. However, no matter how long such treatment at 35 this temperature might be extended, or howoftendt might be repeated, the yield of extracts does not materially increase. After having obtained a first yield of extracts in the way described, the temperature of treatment may be 40 .incr'easing'pressure. By the first treatment all the constituents capable of decomposition at the first. established temperature are extracted 45 from the carbonaceous material and taken in solution by the solvent medium, which protects them against further decomposition, 'and a balance of solid carbonaceous material remains the constituents of which are incapable of decomposition at this temperature. If,- however, the temperature is gradually raised above theflrst 'mentioned level, a temperature will again be reached at which decomposition, indicated by. a sudden rise oi' pressure, reoccurs; Therefore, a

second extraction has to be effected at a temperature above the first extraction temperature but by a few degrees centigrade lower than the second, higher temperature of decomposition established in the way described. Surprisingly, in this secondstage in which the balance of the solid carbonaceous material is being treated at a temperature higher than the first one, a new substantial yield of extracts will be obtained in addition to that obtained during the first treatment. In continuing this. procedure, one may cautiously raise the temperature more and more, obtaining thereby additional yields of extracts until a temperature has been reached at which the last yield of extracts is achieved and no additional amounts of extracts are obtainable, neither by repeating nor by extending the heat treatment at the last and highest temperature nor by further raising this temperature. In the latter case neither a decomposition can be observed (nd sudden increase ofpressure occurs any more) nor will additional extracts result. This last temperature depends upon the composition of the carbonaceous material under treatment, and this and all the foregoing temperatures of treatment, which are close to but below the decomposition temperature of the carbonaceous material under treatment, are to be established for every individual, material in the way described hereinbefore.

If but a small amount of gases is evolvedv thereby and depending upon the nature of the material, the treatment may also be performed at about the various decompositiontemperatures, provided the decomposition of a small part of the constituents is of no consequence.

From this it results that the. extraction may be effected at elevated temperatures which are stepwise or gradually raised so that they. are close to the decomposition temperature of the solid carbonaceous material under treatment and increased with the increasing amount of substance extracted from the material and taken in solution by the solvent media used. The pressure under which, the treatment is performed is usually the normal pressure originating at the temperature applied for the treatment performed in a closed vessel (autoclave). Additional pressure may be applied, however.

' As solvent media, among others, hydrogenated and/or acidic organic oils, alone or in mixture, may be used. By way of example only, a-mixtureof 40 parts naphthalene, 40 parts tetraline and 20 parts of a tar phenol boiling at about 230 C., or a mixture of tetraline and phenols in a ratio of e. g. 1:1, or anthracene oil alone, or

in mixture with phenols or other oils such as tetraline or benzole, may be used. i

In the drawing, a diagram is shown for the treatment of a long-flaming coal with a solvent medium consisting of 40 parts naphthalene, 40 parts tetraline and 20 parts tar phenols obtained by distillation of coal between"180 to 230 C. The long-flaming coal has been powdered or suitably broken up and then mixed with the solvent medium. The amount of solvent medium applied depends upon its nature and that of the carbonaceous material to be extracted. The

with this coal that a firstdecomposition occurs at 330 C. The constituents decomposing at about this temperature having been extracted, the remaining solid carbonaceous material decomposes a second time at 360 C., whereupon after additional extracts have been made at this second temperature range a third, fourth and fifth decomposition temperature occurs at about 380, 400 and 410 C., respectively. Therefore, as the diagram shows, the coal had been heated up to 330 C. when the first extracts were made which may remain in the solvent medium or may be removed'from it. Thereupon the temperature has been gradually or stepwise increased up to 410 to 415 C., and a second, third, fourth and fifth extract were obtained at about 360, 380, 400 and 410 to 415 C., respectively. As shown in the diagram, no additional extracts could be obtained at the sixth and seventh extraction, and therefore further raising of the temperature'or continuation of the treatment at about 410 C. is ineffective. -The ressure in the autoclave was ultimately raised to about 70 to atmospheres. No destruction of the solvent medium took place because of this increased pressure in spite of the temperature being substantially above the normal boiling temperature under atmospheric pressure of some parts of the solvent media. Calculated upon the weight of the original, not disintegrated coal material, by the first extraction about 37% extracts were obtained, by the second extraction additional 8%,

with additional yields at further extractions so that the entire yield of extracts amounted to about 74%. The remaining solid material consisted of cole and ash not capable of further disintegration. As a matter of fact, depending upon the nature of the coal under. treatment,

yields up to 94% may be obtained in this way.

Thus, any and all combustible constituents are extracted from the fuel material, and the high est efiiciency is achieved as far as the given solid fuel material is concerned.

The extracts so obtained are highly active. The extracts being solid at normal temperature up to about 200 C. and'over, coal extracts up to about 230 to 250 0., they can be conveniently separated from the solvents by gradually cooling the solvents still containing the dissolved extracts.

If some undesired amounts of ash and other not disintegrated parts of the carbonaceous material remain in the extracts, they may be separated by centrifugalization or filtration or. by allowing the solution to stand so that the heavier solid particles may precipitate. If, due to the extremely fine dispersion of the impurities referred to none of these methods succeeds, then' the extracts still dissolved in the solvent medium may be filtered under raised pressure and at highly. elevated temperature. Thereby practically pure extracts are obtained, the content of undesirable solid particles being substantially below 1% and, as a great number of investigations have proven, amounting to only a few tenths of one per cent down to less than one tenth of one per cent. For this filtrationja/ny suitable filter and filter material may be used.

obtained therefrom. As average temperatures for this filtering to C., may be mentioned, but higher or lower temperatures may be applied. As the lowest limit a temperature range of about 75 to 100 C. may be given. The

- pressure may be chosen above about 5 atmos- -The solid residue of extraction of carbprihceous material is most suitable as filter materiallfor the extracts.

pheres per square centimeter and very good results have been obtained within the range of 10 to 20 atmospheres. In this way extracts are obtained which are both easily and fully combustible and extremely pure.

These extracts being solid at normal and elevated temperatures up to certain limits mentioned above, are now to be powdered in any suitable way and to any desired fineness. Ball mills may be used and the treatment therein extended suificiently long to obtain the desired size of powder.

As an engine suitable for the powdered carbonaceous extract according to the invenion the motor described in the periodical Oel und Kohle December 1933, pages 135, 136, may be referred to. This motor uses an additional chamber in which measured quantities of powdered solid fuel are delivered ahead of each compression stroke of the piston. The chamber is in open connection with the cylinder so that the compressed and heated air enters'this chamber and gradually heats the fuel deposited therein until its ignition starts automatically and the evolved gases of combustion expand into the cylinder, injecting into it simultaneously the still burning fuel.

such alone or in admixture to any other powdered solid or even liquid fuel material.

In the appended claims the term "so1vent comprises any suitable solvent medium for the' constituents to be extracted, or any mixture of such solvent media.

What I claim is: 1. A carbonaceous fuel material for combustion engines consisting substantially of powdered solid extracts obtained from solid carbonaceous material by treating it in closed vessels with solvents at gradually increasing temperatures and correspondingly rising pressures, said temperatures lying close to the increasing temperatures of decomposition of the carbonaceous material under treatment and raised until no additional yields of extracts are obtained, said extracts separated from the solid residues and powdered.

2. A carbonaceous fuel material for combustion engines consisting substantially of powdered solid extracts obtained from solid carbonaceous material by treating it in closed vessels with solvents at stepwise increasing temperaturesand correspondingly rising pressures, said temperatures lying close to the increasing temperatures of decomposition of the carbonaceous material .yields of extracts are obtained, said extracts separated from the solid residues and powdered.

3. A carbonaceous fuel material for combustion engines consisting substantially of powdered solid extracts obtained from solid carbonaceous material by treating it in closed vessels with solvents at gradually increasing temperatures and correspondingly rising pressures, said temperatures lying close to the increasing temperatures of decomposition of the carbonaceous material under treatment and raised until no additional yields of extracts are obtained, said extracts separated from the solid residues by filtration under elevated temperatures above about C. and under raised pressure above about 5 atmospheres per sq. cm., and thereupon powdered.

4. A carbonaceous fuel material for combustion engines consisting substantially of powdered solid extracts obtained from solid carbonaceous material by treating it in closed vessels with solvents at stepwise increasing temperatures and correspondingly rising pressures, said temperatures lying close to the increasihg temperatures of decomposition of the carbonaceous material under treatment and raised until no additional yields of extracts are obtained, said extracts separated from the solid residues by filtration under elevated temperatures above about 75 0., and under raised pressure above about 5 atmospheres per sq. cm., and thereupon powdered.

5. A method of producing carbonaceous fuel material for combustion engines comprising the steps of extracting solid carbonaceous material with solventsin closed vessels at increasing temperatures and correspondingly rising pressures, said temperatures lying close to the increasing temperatures of decomposition of said carbonaceous material, and raised until no additional yields of extracts are obtained, separating the extracts thus obtained from the solid residues of said material, allowing said extracts to solidify, and thereupon powdering said solid extracts.

6'. A method of producing carbonaceous fuel material for combustion engines comprising the steps of extracting solid carbonaceous material with solvents in closed vessels at increasing temperatures lying'close to the increasing temperatures of decomposition of said carbonaceous material, and raised until no additional yields of extracts are obtained, separating the extracts thus obtained from the solid residues of said material by means of filtration at elevated temperatures aboveabout 75 C. and raised pressure above about 5 atmospheres per sq. cm., allowing said extracts to solidify, and thereupon powder- 

